WO2018211682A1

WO2018211682A1 - Chilling unit and water-circulating temperature-adjustment system

Info

Publication number: WO2018211682A1
Application number: PCT/JP2017/018815
Authority: WO
Inventors: 善生山野; 仁隆門脇; 隆宏秋月; 拓也伊藤; 靖大越
Original assignee: 三菱電機株式会社
Priority date: 2017-05-19
Filing date: 2017-05-19
Publication date: 2018-11-22
Also published as: GB2578373B; GB201913959D0; GB2578373A; JPWO2018211682A1; US11181304B2; JP6707192B2; US20200064031A1

Abstract

A chilling unit and a water-circulating temperature-adjustment system are provided with: a refrigerant circuit including a compressor, a pair of air-side heat exchangers, an expansion valve, and a heat medium-side heat exchanger which are connected by piping to circulate refrigerant; piping for circulating heat medium; a flow passageway switching device for switching the circulation path of refrigerant; a temperature sensor; pressure sensors; and a control device. The control device controls the compressor on the basis of a target exit temperature that is set in advance, a heat medium temperature measured by means of the temperature sensor, and a pressure difference of the heat medium measured by means of the pressure sensors. If the load of a load-side apparatus becomes a low load less than or equal to a lowest capacity of the compressor, start-stop avoidance control is implemented in a state in which the lowest capacity operation of the compressor is maintained, and one of the pair of air-side heat exchangers and the heat medium-side heat exchanger are connected in parallel by means of the flow passageway switching device.

Description

Chilling unit and water circulation temperature control system

The present invention relates to a chilling unit equipped with a refrigeration cycle and a water circulation temperature control system, and in particular, has a structure that stabilizes the supply water temperature even at low loads.

Conventionally, chilling units have been used as heat sources for water circulation temperature control systems. The water circulation temperature control system circulates water in a building or a building of a large-scale commercial facility, and uses the heat for cooling and heating via a fan coil unit or an air handling unit that is a load side device. The water circulation temperature control system is also used for industrial purposes, and circulates water in a factory to cool or adjust the temperature of equipment. In the water circulation temperature control system, a plurality of chilling units including a refrigerant circuit are generally used for one water circulation circuit. And the water piping of each chilling unit is connected via header piping, and the water circulates in the water circulation circuit by the water circulation pump.

Patent Document 1 discloses a chilling unit. Patent Document 1 discloses a system in which two water circuits of water heat exchangers arranged in four refrigerant circuits are connected in parallel, and the parallel water circuits are connected in series. Patent Document 1 describes a technique for changing the combination of water pipes through which water flows according to the operating conditions of a plurality of refrigerant circuits.

Generally, in order to stabilize the supply water temperature in the chilling system and the water circulation temperature control system, it is effective to use a compressor and a water circulation pump corresponding to the inverter. And for those inverter controls, the water temperature and the water pressure before and after the water heat exchanger are measured, and the optimum control for the load is constructed. Moreover, in the water circulation temperature control system having a plurality of chilling units, not only the inverter control but also the number of operating chilling units is controlled to cope with a low load.

International Publication No. 2016/088822

However, in the conventional chilling unit as described above, when the heat amount on the load side falls below the minimum capacity of the compressor, the compressor is started and stopped to adjust the heat amount to match the load. For this reason, the chilling unit frequently starts and stops near the target water temperature, and the supply water temperature may not be stable. Also, frequent start / stop of the compressor reduces the low pressure in the refrigerant circuit, which causes the chilling unit to stop abnormally to avoid freezing of water in the water heat exchanger during cooling operation. It was. Furthermore, if the start and stop are frequently performed in this manner, the life of the compressor is reduced.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a chilling unit and a water circulation temperature control system that can realize a stable supply water temperature even at a low load.

A chilling unit according to the present invention includes a compressor, a pair of air-side heat exchangers, an expansion valve, and a heat medium-side heat exchanger. In the connected and connected piping through which the heat medium that exchanges heat with the refrigerant flows in the heat medium side heat exchanger, and the start / stop avoidance control that is performed when the load of the load side device is equal to or lower than a set value, A flow path switching device for switching the circulation path, a temperature sensor for measuring the temperature of the heat medium at the inlet / outlet of the heat medium side heat exchanger, and a differential pressure of the heat medium at the inlet / outlet of the heat medium side heat exchanger And a control device that controls the compressor, the expansion valve, and the flow path switching device. The control device includes a preset target outlet temperature and a heat medium measured by the temperature sensor. Temperature The compressor is controlled based on the differential pressure of the heat medium measured by the pressure sensor, and when the load of the load side device becomes a low load equal to or lower than the minimum capacity of the compressor, the compressor The start / stop avoidance control is performed in a state where the minimum capacity operation is maintained, and one of the pair of air side heat exchangers and the heat medium side heat exchanger are connected in parallel by the flow path switching device. is there.
Further, the chilling unit according to the present invention includes a compressor, a flow path switching device, an air side heat exchanger, an expansion valve, and a heat medium side heat exchanger, and these are connected by piping to circulate the refrigerant. A refrigerant circuit, a pipe connected to a load-side device and through which a heat medium that exchanges heat with each of the refrigerant in a heat medium side heat exchanger of the two sets of refrigerant circuits, and heat of the two sets of refrigerant circuits For each of the medium side heat exchangers, a plurality of temperature sensors for measuring the temperature of the heat medium at the inlet / outlet, and for each of the heat medium side heat exchangers of the two sets of refrigerant circuits, the differential pressure of the heat medium at the inlet / outlet A plurality of pressure sensors for measuring the pressure, and a control device for controlling the compressor, the flow path switching device, and the expansion valve of each of the two sets of refrigerant circuits, and each of the two sets of refrigerant circuits The flow path switching device includes the heat medium. The heat exchanger switches between a heating-side flow path serving as a condenser and a cooling-side flow path serving as an evaporator, and the control device includes a preset target outlet temperature and a plurality of temperature sensors. The compressor is controlled based on the measured temperature of the heat medium and the differential pressure of the heat medium measured by the plurality of pressure sensors, and the load on the load side device is low enough to be less than the minimum capacity of the compressor. When a load is applied, one of the flow path switching devices of the two sets of refrigerant circuits is switched while maintaining the minimum capacity operation of the compressor.

According to the chilling unit and the water circulation temperature control system of the present invention, the flow path switching device is switched when the load side device becomes a low load. As a result, a surplus of the heating capacity or the cooling capacity is consumed in a part of the plurality of air-side heat exchangers of the chilling unit while the minimum capacity operation of the compressor is maintained. As a result, the chilling unit and the water circulation temperature control system can suppress the thermal start / stop of the compressor and supply a heat medium having a stable temperature to the load-side device even when the load-side device has a low load.

It is a schematic block diagram which shows the structure of the chilling unit which concerns on Embodiment 1 of this invention. It is a block diagram which shows the function of the control apparatus of the chilling unit which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows the refrigerant | coolant flow at the time of the cooling operation of the chilling unit which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control which the control apparatus of the chilling unit which concerns on Embodiment 1 of this invention performs at the time of low load of a load side apparatus. It is a schematic block diagram which shows the structure of the chilling unit which concerns on Embodiment 2 of this invention. It is a flowchart which shows the control which the control apparatus of the chilling unit which concerns on Embodiment 2 of this invention performs at the time of low load of a load side apparatus. It is a schematic block diagram which shows another structure of the chilling unit which concerns on Embodiment 2 of this invention. It is a schematic block diagram of the temperature control system which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
Based on FIG.1 and FIG.2, the structure of a chilling unit is demonstrated. FIG. 1 is a schematic configuration diagram showing a configuration of a chilling unit according to Embodiment 1 of the present invention. FIG. 2 is a block diagram illustrating functions of the control device for the chilling unit according to Embodiment 1 of the present invention.

In the chilling unit 100, the heat medium flowing through the pipe of the heat medium circuit 30 is heated or cooled by the refrigerant flowing through the refrigerant pipe of the refrigerant circuit 10. The heat medium heated or cooled by the chilling unit 100 is sent to the load side device via the heat medium circuit 30, and the heat is used for air conditioning or the like. Any type of refrigerant and heat medium may be used, but for example, chlorofluorocarbon is used as the refrigerant, and water, brine, or the like is used as the heat medium.

(Configuration of chilling unit 100)
In the first embodiment, the chilling unit 100 includes one refrigerant circuit 10 in which a refrigerant circulates and piping of a heat medium circuit 30 in which a heat medium flows. The refrigerant circuit 10 includes a compressor 1, a first flow switching device 2, a pair of air side heat exchangers, a second flow switching device 8, a decompression device, a heat medium side heat exchanger 7, and the like. These are connected via a refrigerant pipe. The chilling unit 100 includes a part of the heat medium circuit 30, and a part of the heat medium circuit 30 includes a circulation pump 31, the heat medium side heat exchanger 7, and a pipe that connects them. included.

The compressor 1 sucks low-temperature and low-pressure refrigerant, compresses the refrigerant, discharges it in a high-temperature and high-pressure state, and circulates the refrigerant. The compressor 1 is composed of an inverter compressor capable of capacity control. The 1st flow-path switching apparatus 2 is comprised, for example with a four-way valve etc., and switches the flow of a refrigerant | coolant by cooling operation and heating operation. The first flow path switching device 2 is provided on the discharge side of the compressor 1, and the destination of the high-temperature and high-pressure refrigerant discharged from the compressor 1 is a pair of air-side heat exchanger or heat medium-side heat exchange. Switch to vessel 7.

The decompression device is composed of an electronic expansion valve or the like, and decompresses the refrigerant to expand it. The decompression device includes an expansion valve 5 and a sub-expansion valve 6. The expansion valve 5 is provided in the refrigerant pipe 15 between the first air side heat exchanger 3 and the second air side heat exchanger 4 and the heat medium side heat exchanger 7, and the sub expansion valve 6 will be described later. The first bypass pipe 16 is provided.

The pair of air-side heat exchangers includes a first air-side heat exchanger 3 and a second air-side heat exchanger 4 that are connected in parallel, exchange heat between the air and the refrigerant, and heat the atmosphere. Absorbs or releases heat to the atmosphere. In the normal control, the first air side heat exchanger 3 and the second air side heat exchanger 4 function as an evaporator during a heating operation and function as a condenser during a cooling operation. Moreover, the 1st air side heat exchanger 3 and the 2nd air side heat exchanger 4 are each attached with the air blower comprised with a propeller fan etc., and air is supplied by an air blower.

1, the first air side heat exchanger 3 and the second air side heat exchanger 4 are connected in parallel. Hereinafter, the refrigerant pipe provided with the first air side heat exchanger 3 is referred to as 13, and the refrigerant pipe provided with the second air side heat exchanger 4 is referred to as 14.

The heat medium side heat exchanger 7 exchanges heat between the refrigerant and the heat medium, and heats or cools the heat medium to a target temperature with the heat of the refrigerant. The heat medium side heat exchanger 7 exchanges heat between the high-temperature and high-pressure refrigerant and the heat medium during the heating operation to increase the temperature of the heat medium, and causes heat exchange between the low-temperature and low-pressure refrigerant and the heat medium during the cooling operation. To lower the temperature of the heating medium.

The second flow path switching device 8 switches the refrigerant circulation path between normal control and start / stop avoidance control described later. The second flow path switching device 8 is composed of, for example, two three-

way valves

8a and 8b. The two three-

way valves

8a and 8b are arranged on the refrigerant pipe 14 so as to sandwich the second air-side heat exchanger 4, and switch the refrigerant flow in the second air-side heat exchanger 4. The three-way valve 8a is provided between the first flow switching device 2 and the second air side heat exchanger 4, and the three-way valve 8b is provided between the second air side heat exchanger 4 and the expansion valve 5. It has been.

The refrigerant circuit 10 has a bypass circuit that bypasses the heat medium side heat exchanger 7. The bypass circuit includes a first bypass pipe 16, a second bypass pipe 17, and a pipe between the three-way valve 8a and the three-way valve 8b in the refrigerant pipe 14 described above. The first bypass pipe 16 connects the refrigerant pipe between the first air side heat exchanger 3 and the second air side heat exchanger 4 and the expansion valve 5 and the three-way valve 8b. The second bypass pipe 17 connects the refrigerant pipe 19 between the heat medium side heat exchanger 7 and the first flow path switching device 2 and the three-way valve 8a. In the refrigerant circuit 10, when the connection state of the second flow path switching device 8 is switched, a part or all of the refrigerant directed to the heat medium side heat exchanger 7 in the main refrigerant circuit flows to the bypass circuit, and normal control and generation are performed. The refrigerant circulation path can be switched by the stop avoidance control.

Here, the start / stop avoidance control becomes an unstable state in which the compressor 1 of the refrigerant circuit 10 repeats start and stop when the load side device connected to the heat medium circuit 30 becomes a low load. This control is performed to avoid this. When the second flow switching device 8 is in the normal control connection state, the refrigerant flows in the second air side heat exchanger 4 on the bypass circuit in the same direction as the first air side heat exchanger 3, and the second When the flow path switching device 8 is in the connected state for start / stop avoidance control, the refrigerant flows in the same direction as the heat medium side heat exchanger 7.

The circulation pump 31 circulates the heat medium in the heat medium circuit 30, so that the heat medium flows between the load-side device and the heat medium-side heat exchanger 7 that are annularly connected via the pipe. . The circulation pump 31 is composed of an inverter type pump, and makes the flow rate of the heat medium variable in multiple stages or continuously. The circulation pump 31 receives a control signal for adjusting the flow rate according to the load from the control device 50 described later, and adjusts the flow rate of the circulating heat medium by driving the frequency of the motor according to the control signal. ing.

In addition, the chilling unit 100 includes a plurality of sensors such as a temperature sensor and a pressure sensor. In the heat medium circuit 30,

temperature sensors

32, 34 and

pressure sensors

33, 35 are arranged in the piping at the entrance / exit of the heat medium side heat exchanger 7. The temperature sensor 32 and the temperature sensor 34 measure the temperature of the heat medium at the inlet / outlet of the heat medium side heat exchanger 7, and the pressure sensor 33 and the pressure sensor 35 are the difference of the heat medium at the inlet / outlet of the heat medium side heat exchanger 7. Measure the pressure. Although not shown, the refrigerant circuit 10 is provided with a low pressure sensor for detecting the refrigerant suction pressure in the suction pipe of the compressor 1, and a high pressure for detecting the refrigerant discharge pressure in the discharge pipe of the compressor 1. A pressure sensor is installed.

The control device 50 is composed of, for example, a microcomputer and controls each actuator of the chilling unit 100. The control device 50 receives pressure information and temperature information of the refrigerant, pressure information and temperature information of the heat medium, and the like from the plurality of sensors described above. The control device 50 performs operation control based on these information acquired from each sensor, preset setting information, a command input by the user, and the like. Specifically, the control device 50 controls the operation, stop, and rotation speed of the compressor 1, adjusts the opening of the decompression device, controls the switching of the first flow path switching device 2 and the second flow path switching device 8, and Then, rotation control and the like of a blower provided in the first air side heat exchanger 3 and the second air side heat exchanger 4 are performed. The control device 50 controls the frequency of the circulation pump 31 and adjusts the flow rate of the heat medium supplied to the heat medium side heat exchanger 7.

Next, the functional configuration of the control device 50 will be described with reference to FIG. The control device 50 includes an operation control unit 51 and a load determination unit 52. The operation control unit 51 calculates an optimum operating condition for setting the heat medium to the target outlet temperature from the preset target outlet temperature of the heat medium and the current temperature and differential pressure of the heat medium at the inlet and outlet. Outputs operation instructions to each actuator. Further, the operation control unit 51 switches between the heating operation and the cooling operation by switching the first flow path switching device 2 and switches the second flow path switching device 8 when performing start / stop avoidance control. Moreover, the operation control part 51 acquires the result of the determination which the load determination part 52 performs, and performs control according to the acquired determination result.

The load determination unit 52 acquires information on the current load on the load side device from the operation control unit 51, and determines the load. Specifically, it is determined whether or not the load has decreased, whether or not the load is less than or equal to the minimum capacity of the compressor 1, or whether or not there is no load. The load determination unit 52 notifies the operation control unit 51 of the determination result. Here, the current load of the load side device may be obtained by the operation control unit 51 by calculation based on information acquired from the load side device, or setting information, control information of each actuator, and information of various sensors.

First, the operation of the chilling unit 100 during normal control will be described. In FIG. 1, an alternate long and short dash line arrow along the heat medium circuit 30 represents the flow of the heat medium, and a solid line arrow and a broken line arrow along the refrigerant circuit 10 represent the refrigerant flow in the normal control cooling operation or heating operation. .

(Normal control)
In the cooling operation, the refrigerant sucked into the compressor 1 is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The gas refrigerant discharged from the compressor 1 is divided into the refrigerant pipe 13 and the refrigerant pipe 14 via the first flow path switching device 2, and the first air-side heat exchanger 3 and the second air-side heat serving as a condenser. The refrigerant flows into the exchanger 4 and is cooled while dissipating heat to the surrounding air, and becomes a high-pressure medium-temperature refrigerant. At this time, the second flow path switching device 8 provided in the refrigerant pipe 14 is in a connected state during normal control. That is, the three-way valve 8a connects the first flow path switching device 2 and the second air side heat exchanger 4, and the three-way valve 8b connects the second air side heat exchanger 4 and the pressure reducing device. . Thereafter, the high-pressure and medium-temperature refrigerant merges, is decompressed by the expansion valve 5 of the decompression device, becomes a low-pressure two-phase state, and flows into the heat medium side heat exchanger 7 that is an evaporator. At this time, the sub-expansion valve 6 is closed, and the refrigerant does not flow into the bypass circuit. The low-pressure two-phase refrigerant absorbs heat from the heat medium flowing through the heat medium circuit 30 in the heat medium side heat exchanger 7 and is evaporated by heating to become a low-pressure and low-temperature gas refrigerant. The gas refrigerant flowing out of the heat medium side heat exchanger 7 passes through the first flow path switching device 2 and then is sucked into the compressor 1 again. On the other hand, the heat medium whose temperature has decreased in the heat medium side heat exchanger 7 is sent from the chilling unit 100 to the load side device.

In the heating operation, the refrigerant sucked into the compressor 1 is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The gas refrigerant discharged from the compressor 1 flows through the first flow path switching device 2 into the heat medium side heat exchanger 7 serving as a condenser, and releases heat to the heat medium flowing through the heat medium circuit 30. It is cooled and becomes a high-pressure medium-temperature refrigerant. Thereafter, the high-pressure and medium-temperature refrigerant is decompressed by the expansion valve 5 of the decompression device, and becomes a low-pressure two-phase state. At this time, the sub-expansion valve 6 is closed, and the second flow path switching device 8 provided in the refrigerant pipe 14 is in a connected state during normal control. Therefore, the refrigerant does not flow in the bypass circuit, and the low-pressure two-phase refrigerant is divided into the refrigerant pipe 13 and the refrigerant pipe 14, and the first air-side heat exchanger 3 and the second air-side heat exchanger 4 serving as an evaporator. Flows into each. Then, the low-pressure two-phase refrigerant is heated and evaporated while absorbing heat from the surrounding air in the first air-side heat exchanger 3 or the second air-side heat exchanger 4, and becomes a low-pressure and low-temperature gas refrigerant. Thereafter, the low-pressure and low-temperature gas refrigerants merge and pass through the first flow path switching device 2 and are sucked into the compressor 1 again. On the other hand, the heat medium whose temperature has increased in the heat medium side heat exchanger 7 is sent from the chilling unit 100 to the load side device.

Further, during the cooling operation and the heating operation, the control device 50 determines the capacity of the compressor 1, the capacity of the circulation pump 31, the opening degree of the expansion valve 5 and the like necessary for setting the heat medium to the target outlet temperature. is doing. Thereby, for example, the compressor 1 is controlled to increase the operation capacity when the load on the load side device is large, and is controlled to decrease the operation capacity when the load on the load side device is small. .

Next, the operation of the chilling unit 100 during start / stop avoidance control will be described with reference to FIG. FIG. 3 is a circuit diagram showing a refrigerant flow during the cooling operation of the chilling unit according to Embodiment 1 of the present invention. In the figure, the solid line arrow represents the refrigerant flow during the cooling operation in the normal control, and the broken line arrow represents the refrigerant flow during the cooling operation in the start / stop avoidance control.

(Start / stop avoidance control)
When the load of the load side device becomes a low load equal to or lower than the minimum capacity of the compressor 1 during the normal control operation, start / stop avoidance control is performed, and the connection state of the second flow path switching device 8 is switched. At this time, the three-way valve 8a connects the second air-side heat exchanger 4 and the second bypass pipe 17, and the three-way valve 8b connects the first bypass pipe 16 and the second air-side heat exchanger 4. . That is, the parallel connection between the first air side heat exchanger 3 and the second air side heat exchanger 4 is released, and the second air side heat exchanger 4 and the heat medium side heat exchanger 7 are connected in parallel. As shown in FIG. 3, the direction of the refrigerant flow in the second air-side heat exchanger 4 is opposite to that during normal control during start / stop avoidance control. At this time, the sub-expansion valve 6 is opened, and the opening degrees of the expansion valve 5 and the sub-expansion valve 6 are adjusted.

In the cooling operation, the low-temperature and low-pressure refrigerant sucked into the compressor 1 is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The gas refrigerant discharged from the compressor 1 flows into the first air-side heat exchanger 3 on the refrigerant pipe 13 through the first flow path switching device 2. The first air-side heat exchanger 3 functions as a condenser, and the gas refrigerant is cooled while dissipating heat to the surrounding air, and becomes a high-pressure medium-temperature refrigerant. Part of the high-pressure medium-temperature refrigerant that has flowed out of the first air-side heat exchanger 3 is decompressed by the expansion valve 5, enters a low-pressure two-phase state, flows into the heat medium-side heat exchanger 7, and the rest The refrigerant is depressurized by the sub-expansion valve 6, becomes a low-pressure two-phase state, and flows into the second air-side heat exchanger 4. During the cooling operation in the start / stop avoidance control, both the heat medium side heat exchanger 7 and the second air side heat exchanger 4 function as an evaporator. The low-pressure two-phase refrigerant flowing into the heat medium side heat exchanger 7 absorbs heat from the heat medium flowing through the heat medium circuit 30 and is evaporated by heating to become a low-pressure and low-temperature gas refrigerant. The low-pressure two-phase refrigerant flowing into the second air-side heat exchanger 4 absorbs heat from the surrounding air and is evaporated by heating to become a low-pressure and low-temperature gas refrigerant. The amount of refrigerant flowing through the heat medium side heat exchanger 7 and the amount of refrigerant flowing through the bypass circuit are adjusted by the opening degree of the expansion valve 5 and the sub expansion valve 6. Then, the gas refrigerant that has flowed out of the heat medium side heat exchanger 7 and the gas refrigerant that has flowed out of the second air side heat exchanger 4 merge, and are sucked into the compressor 1 again via the first flow path switching device 2. Is done. On the other hand, the heat medium whose temperature has decreased in the heat medium side heat exchanger 7 is sent from the chilling unit 100 to the load side device.

When the start / stop avoidance control is performed in this way, the amount of refrigerant flowing through the heat medium side heat exchanger 7 can be adjusted. For this reason, even if the operating capacity of the compressor 1 is the minimum capacity, the chilling unit 100 can be controlled to further reduce the amount of heat exchange between the refrigerant and the heat medium, and can cope with a low load.

FIG. 4 is a flowchart showing the control performed by the chilling unit control apparatus according to Embodiment 1 of the present invention when the load side device is under low load.

During operation of the chilling unit, the operation control unit 51 obtains the load of the load side device and controls each actuator according to the load. The load determination unit 52 acquires load information from the operation control unit 51, and determines whether or not the load on the load side device has decreased (step ST101). At this time, the load determination unit 52 compares the information of the load acquired this time with the information of the load acquired last time, or averages the load for a predetermined time and compares the current average with the previous average. The load reduction determination in step ST101 may be performed. When the load decreases (step ST101; YES), the load determination unit 52 further determines whether or not the load on the load side device is a low load equal to or lower than the minimum capacity of the compressor 1 (step ST102). . When determining that the load is low (step ST102; YES), the load determination unit 52 notifies the operation control unit 51 of the determination result. Then, start / stop avoidance control is performed by the operation control unit 51. On the other hand, when it is determined that the load has not decreased in the load decrease determination (step ST101; NO), or when it is determined that the load is not low in the low load determination in step ST102 (step ST102). NO), the load determination unit 52 notifies the operation control unit 51 of the determination result. Then, the normal control is continued by the operation control unit 51. During operation, the load determination unit 52 acquires the load information of the load side device from the operation control unit 51, repeats the determinations of step ST101 and step ST102, and monitors the decrease in load.

In the start / stop avoidance control, the operation control unit 51 keeps the second flow path switching device 8 from the normal control connection state in order to consume the surplus heating or cooling capacity while maintaining the minimum capacity operation of the compressor 1. The connection state of start / stop avoidance control is switched (step ST103). For example, when start / stop avoidance control is performed during the cooling operation, the first air-side heat exchanger 3 serves as a condenser and the second air-side heat exchanger 4 serves as an evaporator. Perform heat exchange at. Further, the operation control unit 51 adjusts the opening degree of the expansion valve 5 and the sub-expansion valve 6 so that the amount of heat exchanged by the heat medium side heat exchanger 7 becomes the amount of heat commensurate with the load of the load side device ( Step ST104). Operation control part 51 should just control so that the amount of refrigerant which flows into heat carrier side heat exchanger 7 may decrease, so that the opening of expansion valve 5 is made small, so that the load of load side equipment is small.

Next, the load determination unit 52 determines whether or not the load on the load side device is 0 (step ST105). If the load on the load side device is not 0 (step ST105; NO), the operation control unit 51 repeatedly adjusts the opening degrees of the expansion valve 5 and the sub-expansion valve 6 (step ST104). On the other hand, when the load of the load side device is 0 (step ST105; YES), the operation control unit 51 fully closes the expansion valve 5 (step ST106). When the expansion valve 5 is fully closed, all of the refrigerant going to the heat medium side heat exchanger 7 flows to the bypass circuit, and is exchanged with the atmosphere by the second air side heat exchanger 4.

Thus, even when there is no load, the excess of the heating or cooling capacity is offset by the first air-side heat exchanger 3 and the second air-side heat exchanger 4 exchanging heat with the atmosphere. Here, when there is no load on the heat medium circuit 30 side, in order to offset the surplus capacity in the refrigerant circuit 10, the first air side heat exchanger 3 and the second air side heat exchanger 4 are: It is desirable that the same heat exchange capability can be exhibited.

In addition, when the load side device is low in the cooling operation, the opening degree of the expansion valve 5 is adjusted so as to maintain the refrigerant temperature (for example, 0 ° C. or higher) at which the heat medium side heat exchanger 7 does not freeze. Yes. By adjusting the expansion valve 5 in this way, the chilling unit 100 can also make the flow rate of the heat medium extremely low based on the pressure difference between the

pressure sensors

33 and 35 in the heat medium circuit 30. The power of the circulation pump 31 can be reduced.

In addition, although the case where the 1st air side heat exchanger 3 and the 2nd air side heat exchanger 4 were connected in parallel was demonstrated to the example, it is not limited to this in particular. If the second air side heat exchanger 4 functions as described above in the normal control and the start / stop avoidance control, and the amount of refrigerant flowing through the heat medium side heat exchanger 7 can be adjusted in the start / stop avoidance control, Any circuit configuration may be used.

As described above, in the first embodiment, the chilling unit 100 includes the compressor 1, a pair of air side heat exchangers (for example, the first air side heat exchanger 3 and the second air side heat exchanger 4), and expansion. A refrigerant circuit 10 having a valve 5 and a heat medium side heat exchanger 7, a pipe through which the heat medium flows, a flow path switching device (second flow path switching device 8), a control device 50, and the like are provided. . Then, the control device 50 switches the flow path switching device (second flow path switching device 8) in a state where the minimum capacity operation of the compressor 1 is maintained when the load side device becomes a low load, and a pair of air One side heat exchanger (second air side heat exchanger 4) and the heat medium side heat exchanger 7 are connected in parallel.

Thereby, when the load side apparatus becomes low load, the chilling unit 100 maintains the minimum capacity operation of the compressor 1 and the surplus heating capacity or cooling capacity in the second air side heat exchanger 4. Can be consumed. Therefore, the chilling unit 100 can suppress the thermal start / stop of the compressor 1 and supply a heat medium having a stable temperature to the load side device even at a low load.

One of the pair of air side heat exchangers (second air side heat exchanger 4) and the other (first air side heat exchanger 3) are connected in parallel. When the device (second flow path switching device 8) is switched, the parallel connection between one and the other of the pair of air-side heat exchangers is released.

Thus, the second air-side heat exchanger 4 assists the first air-side heat exchanger 3 in the normal control and the heat medium in the start / stop avoidance control by the second flow path switching device 8 that switches the circulation path of the refrigerant. The side heat exchanger 7 can be assisted to consume the excess heating or cooling capacity.

The expansion valve 5 is provided in the refrigerant pipe 15 between the pair of air side heat exchangers (the first air side heat exchanger 3 and the second air side heat exchanger 4) and the heat medium side heat exchanger 7. The control device 50 fully closes the expansion valve 5 when the load on the load side device becomes zero.

Thereby, at the time of low load, the second flow path switching device 8 is switched to start / stop avoidance control while the minimum capacity operation of the compressor 1 is maintained, and when the load becomes zero, the expansion valve 5 is fully closed. . For this reason, when there is no load, heat exchange in the heat medium side heat exchanger 7 is not performed, and the surplus of the heating or cooling capacity is offset by the second air side heat exchanger 4 exchanging heat with air. The Therefore, even when there is no load, the chilling unit 100 can suppress the thermal start / stop of the compressor 1 and supply a heat medium having a stable temperature to the load side.

Further, the chilling unit 100 further includes an inverter-type circulation pump 31 that makes the flow rate of the heat medium variable, and the control device 50 has a low load on the load side device in the cooling operation for cooling the heat medium. Moreover, the opening degree of the expansion valve 5 is controlled so that the refrigerant temperature at which the heat medium side heat exchanger 7 is not frozen is maintained.

Thereby, even at the time of low load, the low pressure is stabilized and the refrigerant temperature is stabilized by the control that does not start and stop the compressor 1. As a result, the flow rate of the heat medium can be made extremely low without causing an abnormal stop or the like even at a low load. Further, since the flow rate of the heat medium or the refrigerant flowing through the heat medium side heat exchanger 7 can be adjusted by the flow rate variable circulation pump 31 and the variable opening degree expansion valve 5, the chilling unit 100 has a load on the load side device. The amount of heat can be adjusted according to the load even in a low load state where there is little. Thereby, the chilling unit 100 can reduce the power of the circulation pump 31.

Embodiment 2. FIG.
A chilling unit 200 according to the second embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic configuration diagram showing the configuration of the chilling unit according to Embodiment 2 of the present invention. FIG. 6 is a flowchart showing the control performed by the chilling unit control apparatus according to Embodiment 2 of the present invention when the load side device is under low load. Hereinafter, in the chilling unit 200 of the second embodiment, a configuration different from the case of the first embodiment will be described, and the description of the corresponding configuration will be omitted.

In Embodiment 2, the chilling unit 200 has two refrigerant circuits. Each

refrigerant circuit

210a, 210b includes compressors 1a, 1b, first flow

path switching devices

2a, 2b, air

side heat exchangers

3a, 3b,

expansion valves

5a, 5b, and heat medium side heat exchanger 7a. , 7b and the like. That is, the chilling unit 200 of the second embodiment is not provided with the second air side heat exchanger 4, the second flow path switching device 8, the bypass circuit, and the sub expansion valve 6 of the first embodiment. FIG. 5 shows a case where the heat medium

side heat exchangers

7 a and 7 b of the

refrigerant circuits

210 a and 210 b are connected in parallel in the heat medium circuit 230.

In the second embodiment, the circulation pump 31 is provided upstream of the heat medium side heat exchanger 7a and the heat medium side heat exchanger 7b in the heat medium circuit 230. Moreover, the

temperature sensors

32 and 34 and the

pressure sensors

33 and 35 are provided for each of the heat medium

side heat exchangers

7a and 7b, and for each of the heat medium

side heat exchangers

7a and 7b, the temperature of the heat medium at the inlet / outlet, and The differential pressure of the heat medium at the inlet / outlet is measured. Further, each

refrigerant circuit

210a, 210b has a low-pressure sensor that detects the suction pressure of the compressors 1a, 1b and a high-pressure that detects the discharge pressure of the compressors 1a, 1b, as in the first embodiment. A pressure sensor or the like is installed.

First, the operation during normal control of the chilling unit 200 will be described. In FIG. 5, the dashed-dotted arrow along the heat medium circuit 230 represents the flow of the heat medium. Moreover, the broken line arrow along the refrigerant circuit 210a represents the flow of the refrigerant when performing the heating operation, and the solid line arrow along the refrigerant circuit 210b represents the flow of the refrigerant when performing the cooling operation.

(Normal control)
In the cooling operation, the refrigerant sucked into the compressor 1b is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The gas refrigerant discharged from the compressor 1b passes through the first flow path switching device 2b, flows into the air-side heat exchanger 3b serving as a condenser, radiates heat to the surrounding air, and becomes a high-pressure medium-temperature refrigerant. The high-pressure medium-temperature refrigerant that has flowed out of the air-side heat exchanger 3b is decompressed by the expansion valve 5b, becomes a low-pressure two-phase state, and flows into the heat medium-side heat exchanger 7b that is an evaporator. In the heat medium side heat exchanger 7b, the low-pressure two-phase refrigerant absorbs heat from the heat medium flowing through the heat medium circuit 230 and is evaporated by heating to become a low-pressure and low-temperature gas refrigerant. The gas refrigerant that has flowed out of the heat medium side heat exchanger 7b passes through the first flow path switching device 2b and then is sucked into the compressor 1b again. On the other hand, the heat medium that releases heat in the heat medium side heat exchanger 7b and the temperature is lowered is sent from the chilling unit 200 to the load side device.

In the heating operation, the refrigerant sucked into the compressor 1a is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The gas refrigerant discharged from the compressor 1a flows into the heat medium side heat exchanger 7a serving as a condenser via the first flow path switching device 2a, and releases heat to the heat medium flowing through the heat medium circuit 30, It becomes a high pressure and medium temperature refrigerant. The high-pressure medium-temperature refrigerant that has flowed out of the heat medium side heat exchanger 7a is decompressed by the expansion valve 5a to be in a low-pressure two-phase state, and flows into the air-side heat exchanger 3a. In the air-side heat exchanger 3a, the low-pressure two-phase refrigerant is heated and evaporated while absorbing heat from the surrounding air, and becomes a low-pressure and low-temperature gas refrigerant. The low-pressure and low-temperature refrigerant that has flowed out of the air-side heat exchanger 3a passes through the first flow path switching device 2a and is again sucked into the compressor 1a. On the other hand, the heat medium that has absorbed heat in the heat medium side heat exchanger 7a and whose temperature has risen is sent from the chilling unit 200 to the load side device.

Further, during the cooling operation and the heating operation, the control device 250 determines the capacity of the compressor 1, the capacity of the circulation pump 31, the opening degree of the expansion valve 5, and the like necessary for setting the heat medium to the target outlet temperature. is doing. In the second embodiment, since the chilling unit 200 has two refrigerant circuits, by sharing the load, it is possible to cope with a larger load than the chilling unit 100 configured by one circuit.

Next, the control at the time of low load performed by the control device 250 will be described based on FIG. Here, it is assumed that the chilling unit 200 performs a cooling operation under normal control by two refrigerant circuits 210a and 210, and the compressors 1a and 1b are operated at a minimum capacity.

During operation of the chilling unit, the operation control unit 51 obtains the load of the load side device and controls each actuator according to the load. The load determination unit 52 acquires load information from the operation control unit 51, and determines whether or not the load on the load side device has decreased (step ST201). At this time, the load determination unit 52 compares the information of the load acquired this time with the information of the load acquired last time, or averages the load for a predetermined time and compares the current average with the previous average. The load reduction determination in step ST201 may be performed. When the load decreases (step ST201; YES), the load determination unit 52 further determines whether or not the load on the load side device is a low load equal to or less than the minimum capacity of the compressors 1a and 1b (step ST201). ST202). When determining that the load is low (step ST202; YES), the load determination unit 52 notifies the operation control unit 51 of the determination result. Then, start / stop avoidance control is performed by the operation control unit 51. On the other hand, when it is determined that the load has not decreased in the load decrease determination (step ST201; NO), or when it is determined that the load is not low in the low load determination in step ST202 (step ST202). NO), the load determination unit 52 notifies the operation control unit 51 of the determination result. Then, the normal control is continued by the operation control unit 51. During operation, the load determination unit 52 acquires information on the load of the load side device from the operation control unit 51, repeats the determinations of step ST201 and step ST202, and monitors the decrease in load.

In the start / stop avoidance control, the operation control unit 51 consumes the excess cooling capacity while maintaining the minimum capacity operation of the compressors 1a and 1b. Is switched to the connection state of the heating operation (step ST203). Further, the operation control unit 51 adjusts the operation capacities of the compressors 1a and 1b so that the amount of heat exchanged by the heat medium

side heat exchangers

7a and 7b becomes the amount of heat commensurate with the load of the load side equipment (step). ST204). For example, the operation control unit 51 may control the compressors 1a and 1b so that the difference between the cooling capacity of the refrigerant circuit 210b and the heating capacity of the refrigerant circuit 210a becomes smaller as the load on the load side device is smaller. As described above, when the start / stop avoidance control is performed during the cooling operation, the heat medium is heated by one refrigerant circuit 210a and the heat medium is cooled by the other refrigerant circuit 210b. The total amount of heat exchanged between them can be made smaller than in normal control.

Next, the load determination unit 52 determines whether or not the load on the load side device is 0 (step ST205). When the load on the load side device is not 0 (step ST205; NO), the operation control unit 51 repeatedly adjusts the operation capacities of the compressors 1a and 1b (step ST204). On the other hand, when the load on the load side device is 0 (step ST205; YES), the operation capacity of the compressors 1a and 1b is adjusted by the operation control unit 51 (step ST206). Specifically, at least one of the compressor 1a and the compressor 1b is adjusted so that the cooling capacity of the refrigerant circuit 210b performing the cooling operation is equal to the heating capacity of the refrigerant circuit 210a performing the heating operation. Is done. For this reason, the total amount of heat exchanged between the refrigerant circuit 210a and the refrigerant circuit 210b and the heat medium circuit 230 is offset.

Further, when the load side device is low in the cooling operation, the expansion valve 5b may be adjusted so that the refrigerant temperature (for example, 0 ° C. or higher) at which the heat medium side heat exchanger 7b on the cooling operation side does not freeze is maintained. . By adjusting the expansion valve 5b in this way, the chilling unit 100 can also make the flow rate of the heat medium extremely low based on the pressure difference between the

pressure sensors

33 and 35 in the heat medium circuit 230. The power of the circulation pump 31 can be reduced.

In the second embodiment, the case where the heat medium side heat exchanger 7a and the heat medium side heat exchanger 7b are connected in parallel in the heat medium circuit 230 has been described. However, the heat medium side heat exchanger 7a and the heat medium side heat exchanger 7a The heat medium side heat exchanger 7b may be connected in series.

FIG. 7 is a schematic configuration diagram showing another configuration of the chilling unit according to Embodiment 2 of the present invention. In the chilling unit 300 shown in FIG. 7, the heat medium side heat exchanger 7 a and the heat medium side heat exchanger 7 b are connected in series in the heat medium circuit 330. Then, the heat medium side heat exchanger switches the first flow path switching device 2a of the refrigerant circuit 210a on the upstream side of the flow of the heat medium to the heating side to heat the heat medium, and the refrigerant circuit 210b on the downstream side That is, the heat medium is cooled by the refrigerant circuit 210b during the cooling operation.

Thereby, in the heat medium circuit 330, the heat medium heated by the upstream heat medium side heat exchanger 7a is cooled by the downstream heat medium side heat exchanger 7b. In comparison, it is possible to avoid a significant decrease in the temperature of the heat medium. Accordingly, the chilling unit 300 can realize heating or cooling according to the load without freezing even when the heat medium is set to an extremely low flow rate at the time of low load.

As described above, in the second embodiment, the

chilling units

200 and 300 include the compressors 1a and 1b, the flow path switching devices (first flow

path switching devices

2a and 2b), the air

side heat exchangers

3a and 3b, and the expansion. Two sets of

refrigerant circuits

210a and 210b, to which the

valves

5a and 5b and the heat medium

side heat exchangers

7a and 7b are connected by piping, a pipe through which the heat medium flows, a control device 250, and the like are provided. The flow path switching device (first flow

path switching devices

2a and 2b) includes a heating-side flow path in which the heat medium

side heat exchangers

7a and 7b serve as condensers and a cooling-side flow path as the evaporator. Switch. In addition, when the load-side equipment becomes a low load, the control device 250 maintains the minimum capacity operation of the compressors 1a and 1b and the flow of one of the two refrigerant circuits (for example, the refrigerant circuit 210a). The path switching device (first flow path switching device 2a) is switched.

Accordingly, the

chilling units

200 and 300 can heat or cool the entire unit by a combination of the operation of the two

refrigerant circuits

210a and 210b while the compressors 1a and 1b are operated when the load-side equipment becomes a low load. A surplus of capacity can be consumed. Therefore, the

chilling units

200 and 300 can suppress the thermal start / stop of the compressors 1a and 1b and supply a heat medium having a stable temperature to the load side even when the load side device has a low load.

In addition, when the load on the load side device becomes zero, the control device 250 determines that the heating capacity of the refrigerant circuit 210a that performs the heating operation and the cooling capacity of the refrigerant circuit 210b that performs the cooling operation. The operating capacities of the compressors 1a and 1b of at least one of the two

refrigerant circuits

210a and 210b are controlled so as to be equal.

Thereby, when the load becomes low, the refrigerant flow of one refrigerant circuit is switched in a state where the compressors 1a and 1b are operated, and when the load becomes zero, the heating capacity and the cooling capacity are equal. The operating capacities of the compressors 1a and 1b are controlled so that For this reason, the amount of heat exchanged by the heat medium side heat exchanger 7a and the heat medium side heat exchanger 7b is offset. Therefore, the

chilling units

200 and 300 can suppress the thermal start / stop of the compressors 1a and 1b and supply a heat medium having a stable temperature to the load side device even when there is no load on the load side device.

Further, the

chilling units

200 and 300 further include an inverter-type circulation pump 31 that makes the flow rate of the heat medium variable. The control device 250 has a low load on the load side device in the cooling operation for cooling the heat medium. In some cases, the opening degree of the expansion valve 5b of the refrigerant circuit 210b is set so that the heat medium side heat exchanger 7b of the refrigerant circuit (for example, the refrigerant circuit 210b) performing the cooling operation maintains a refrigerant temperature that does not freeze. Control.

As a result, even when the load-side equipment is lightly loaded, the low-pressure pressure is stabilized by the control that does not start and stop the compressors 1a and 1b, and the refrigerant temperature is stabilized, so that the flow rate of the heat medium can be reduced without causing an abnormal stop or the like. An extremely low flow rate can be achieved. Further, since the flow rate of the heat medium or the refrigerant flowing through the heat medium

side heat exchangers

7a and 7b can be adjusted by the flow rate variable circulation pump 31 and the variable opening

degree expansion valves

5a and 5b, the

chilling units

200 and 300 The amount of heat can be adjusted according to the load even in a low load state in which there is almost no load on the load side device. Thereby, the

chilling units

200 and 300 can reduce the power of the circulation pump 31.

In addition, the heat medium

side heat exchangers

7a and 7b of the two sets of refrigerant circuits are connected in series in the heat medium circuit 330, and the controller 250 reduces the load on the load side device in the cooling operation for cooling the heat medium. When it is a load, the flow path switching device (first flow path switching device 2a) of the refrigerant circuit (for example, the refrigerant circuit 210a) in which the heat medium

side heat exchangers

7a and 7b are arranged on the upstream side is heated. Switch to the side.

Thereby, in the heat medium circuit 330, the heat medium cooled by the downstream refrigerant circuit 210b is mixed with the heat medium heated by the upstream refrigerant circuit 210a, so that the temperature of the heat medium does not drop significantly. . For this reason, it is possible to provide the chilling unit 300 that does not freeze even when the heat medium is at a very low flow rate at the time of low load.

In the above-described start / stop avoidance control, the operation of one refrigerant circuit 210a is switched from the state where both the compressor 1a and the compressor 1b are operating at the minimum capacity operation, but it can cope with a low load. Any control can be used. For example, the control device 250 first stops the operation of one refrigerant circuit 210a when the load is lower than a set value, and then stops when the load is less than the minimum capacity of the compressor 1b. The refrigerant circuit 210a that has been used may be controlled to operate with a refrigerant flow in a direction opposite to that of the refrigerant circuit 210b.

Embodiment 3 FIG.
FIG. 8 is a schematic configuration diagram of a temperature control system according to Embodiment 3 of the present invention. As shown in FIG. 8, the water circulation temperature control system 500 is configured by using a plurality of chilling units 100 of the first embodiment for one water circuit 530.

The water circulation temperature control system 500 includes a plurality of

chilling units

100a, 100b, and 100c, a plurality of load-

side devices

90a, 90b, and 90c, a header pipe 540a, a header pipe 540b, and the like. Hereinafter, when it is not necessary to particularly distinguish the chilling unit 100a, the chilling unit 100b, and the chilling unit 100c, each will be described as the chilling unit 100. In addition, when there is no need to particularly distinguish the load side device 90a, the load side device 90b, and the load side device 90c, each will be described as the load side device 90.

The plurality of load-

side devices

90a, 90b, 90c and the pipes through which the heat medium flows in the plurality of

chilling units

100a, 100b, 100c are connected via the header pipe 540a and the header pipe 54, so that the heat medium A water circuit 530 in which certain water circulates is configured. Further, the water circulation temperature control system 500 includes a system control device 510, and the system control device 510 is connected to the control device 50 of each chilling unit 100 and each load side device 90 so as to be communicable.

When the load on the load-side device 90 is reduced, the system control device 510 reduces the number of operating chilling units 100 according to the load, and finally only one chilling unit 100 is operating. To. When the load on the load-side device 90 further decreases to a low load equal to or lower than the minimum capacity of the compressor 1, the system control device 510 sends the chilling unit 100 (for example, the chilling unit 100a) in operation to The start / stop avoidance control as described above is performed.

The water circulation temperature control system 500 may use a plurality of chilling units 200 or chilling units 300 according to the second embodiment instead of using a plurality of chilling units 100 according to the first embodiment. In this case, two of the plurality of

chilling units

200 and 300 are operated at a low load.

As described above, the water circulation temperature control system 500 uses the

chilling units

100, 200, and 300 according to the first embodiment or the second embodiment, so that even when the load on the load side device 90 is reduced, It is possible to cope with water flow with extremely low flow rate by suppressing the start and stop of the thermo. And the water circulation temperature control system 500 can adjust the calorie | heat amount of a chilling unit according to a load also in the low load state with little load of the load side apparatus 90. FIG. For this reason, in the water circulation temperature control system 500, there is no need to install a bypass pipe between the header pipe 540a and the header pipe 540b, a cushion tank, or the like provided in the conventional water circulation temperature control system.

As described above, in the third embodiment, the water circulation temperature control system 500 includes the

chilling units

100, 200, 300, and a plurality of units arranged with respect to one heat medium circuit (water circuit 530).

Header piping

540a and 540b to which the piping of the chilling unit is connected.

Accordingly, in the plurality of

chilling units

100a, 100b, and 100c, as described above, even when the load of the load-side device 90 is equal to or less than the minimum capacity of the compressor 1, the low-pressure pressure is controlled by the control that does not start and stop the compressor 1. Stable and the refrigerant temperature is stable. For this reason, the water circulation temperature control system 500 can suppress the occurrence of an abnormal stop to make the heat medium have an extremely low flow rate, and can adjust the heat amount of the chilling unit 100 according to the load even in a low load state. Therefore, the water circulation temperature control system 500 does not need to install a bypass pipe and a cushion tank in the water circuit 530 on the load side, can cope with a low amount of water, and can simplify the system configuration.

The embodiment of the present invention is not limited to the above embodiment, and various changes can be made. For example, the above description is about an air-cooled chilling unit in which the compressor does not start and stop even at low loads, but it goes without saying that it can also be used for other water-cooled chilling units, direct expansion refrigeration units, and air conditioners. Yes.

In addition, as an explanation of a plurality of refrigerant circuits, a two refrigerant circuit is taken as an example, but a unit having three refrigerant circuits, four refrigerant circuits, or more refrigerant circuits can be applied in consideration of the balance between cooling and heating. It is.

1, 1a, 1b compressor, 2, 2a, 2b, first flow switching device, 3, first air side heat exchanger, 3a, 3b, air side heat exchanger, 4, second air side heat exchanger, 5, 5a , 5b expansion valve, 6 sub-expansion valve, 7, 7a, 7b heat medium side heat exchanger, 8 second flow path switching device, 8a, 8b three-way valve, 10, 210a, 210b refrigerant circuit, 13, 14, 15, 19 refrigerant piping, 16 first bypass pipe, 17 second bypass pipe, 30, 230, 330 heat medium circuit, 31 circulation pump, 32, 34 temperature sensor, 33, 35 pressure sensor, 50, 250 control device, 51 operation control Part, 52 load judgment part, 90 (90a, 90b, 90c) load side equipment, 100, 100a, 100b, 100c, 200 chilling unit, 500 water circulation temperature control system, 510 System controller, 530 water circuit, 540a, 540b header pipe.

Claims

A refrigerant circuit having a compressor, a pair of air-side heat exchangers, an expansion valve, and a heat medium-side heat exchanger, these being connected by piping and circulating the refrigerant;
A pipe connected to a load side device, through which a heat medium that exchanges heat with the refrigerant in the heat medium side heat exchanger flows;
In the start / stop avoidance control that is performed when the load of the load side device is equal to or less than a set value, a flow path switching device that switches a circulation path of the refrigerant
A temperature sensor for measuring the temperature of the heat medium at the inlet / outlet of the heat medium side heat exchanger;
A pressure sensor for measuring a differential pressure of the heat medium at an inlet / outlet of the heat medium side heat exchanger;
A controller for controlling the compressor, the expansion valve, and the flow path switching device;
The control device includes:
Controlling the compressor based on a preset target outlet temperature, a temperature of the heat medium measured by the temperature sensor, and a pressure difference of the heat medium measured by the pressure sensor,
When the load of the load side device becomes a low load equal to or lower than the minimum capacity of the compressor, the start / stop avoidance control is performed while maintaining the minimum capacity operation of the compressor, and the flow path switching device A chilling unit that connects one of the pair of air side heat exchangers and the heat medium side heat exchanger in parallel.
The one and the other of the pair of air side heat exchangers are connected in parallel, and in the start / stop avoidance control, when the flow path switching device is switched, the one of the pair of air side heat exchangers and The chilling unit according to claim 1, wherein the parallel connection with the other is released.
The expansion valve is provided in a refrigerant pipe between the pair of air side heat exchangers and the heat medium side heat exchanger,
The chilling unit according to claim 1, wherein the control device fully closes the expansion valve when the load of the load side device becomes zero.
An inverter-type circulation pump that makes the flow rate of the heat medium variable;
In the cooling operation for cooling the heat medium, the control device controls the expansion valve so as to maintain a refrigerant temperature at which the heat medium side heat exchanger does not freeze when the load on the load side device is low. The chilling unit according to any one of claims 1 to 3, wherein the opening is controlled.
A compressor, a flow path switching device, an air-side heat exchanger, an expansion valve, and a heat medium-side heat exchanger, and two sets of refrigerant circuits that are connected by piping to circulate the refrigerant;
A pipe connected to a load side device, through which a heat medium that exchanges heat with the respective refrigerant in the heat medium side heat exchanger of the two sets of refrigerant circuits, and
For each of the heat medium side heat exchangers of the two sets of refrigerant circuits, a plurality of temperature sensors that measure the temperature of the heat medium at the entrance and exit,
For each of the heat medium side heat exchangers of the two sets of refrigerant circuits, a plurality of pressure sensors that measure the differential pressure of the heat medium at the inlet and outlet;
A controller for controlling the compressor, the flow path switching device and the expansion valve of each of the two sets of refrigerant circuits;
Each of the flow path switching devices of the two sets of refrigerant circuits switches between a heating side flow path in which the heat medium side heat exchanger serves as a condenser and a cooling side flow path as an evaporator,
The control device includes:
Controlling the compressor based on a preset target outlet temperature, the temperature of the heat medium measured by the plurality of temperature sensors, and the pressure difference of the heat medium measured by the plurality of pressure sensors,
When the load on the load side device is a low load equal to or lower than the minimum capacity of the compressor, the flow path switching device of one of the two sets of refrigerant circuits is maintained in a state where the minimum capacity operation of the compressor is maintained. Switch chilling unit.
When the load on the load side device becomes zero, the control device makes the heating capacity of the refrigerant circuit performing the heating operation equal to the cooling capacity of the refrigerant circuit performing the cooling operation. The chilling unit according to claim 5, wherein an operation capacity of the compressor of at least one of the two sets of refrigerant circuits is controlled.
An inverter-type circulation pump that makes the flow rate of the heat medium variable;
In the cooling operation for cooling the heat medium, the control device is a refrigerant in which the heat medium side heat exchanger of the refrigerant circuit performing the cooling operation does not freeze when the load on the load side device is a low load. The chilling unit according to claim 5 or 6, wherein the opening degree of the expansion valve of the refrigerant circuit is controlled so as to maintain the temperature.
The heat medium side heat exchangers of the two sets of refrigerant circuits are connected in series in the heat medium circuit formed by the piping,
In the cooling operation for cooling the heat medium, when the load on the load-side device is a low load, the control device performs the flow of the refrigerant circuit in which the heat medium-side heat exchanger is arranged upstream. The chilling unit according to any one of claims 5 to 7, wherein the path switching device is switched to the heating side.
A chilling unit according to any one of claims 1 to 8, wherein a plurality of units are arranged for one heat medium circuit;
A water circulation temperature control system comprising: a header pipe to which each of the pipes of the plurality of chilling units is connected.